Characterization of complex formation between lipopolysaccharide and lysozyme

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• Bacterial lipopolysaccharide (LPS) is a key component of Gram-negative bacterial outer membranes, eliciting potent immune responses.
• Lysozyme (LZM) is an enzyme with bactericidal properties, crucial in innate immunity.
• Understanding LZM-LPS interactions is vital for developing novel antimicrobial and anti-inflammatory strategies.

Purpose of the Study:

• To characterize the binding interaction between lysozyme (LZM) and bacterial lipopolysaccharide (LPS).
• To elucidate the impact of LZM-LPS complex formation on the biological and enzymatic activities of both molecules.
• To investigate the binding modes and influencing factors such as temperature, salt concentration, and time.

Main Methods:

• Utilized dansylated lysozyme (LZM) to monitor binding through fluorescence intensity (Fl-intensity) changes.
• Assessed enzyme inhibition of LZM and biological activities of LPS upon complex formation.
• Investigated the effects of varying reaction temperatures, salt concentrations, and incubation times on complex stability and formation.

Main Results:

• LZM binding to LPS inhibited the biological activities of LPS and the enzymatic activity of LZM.
• Complex formation was time-dependent and stabilized faster at higher temperatures (70°C > 50°C > 37°C).
• Binding was dependent on salt concentration, with no complex observed above 0.5M NaCl, and multiple binding modes were identified.

Conclusions:

• LZM and LPS interact through multiple binding modes, affecting their respective functions.
• Temperature and salt concentration are critical factors influencing LZM-LPS complex formation and stability.
• The findings provide insights into the molecular mechanisms underlying LZM-LPS interactions and their functional consequences.